Since the era of computers becoming popular and the Internet being rapidly developed, the relationship between mankind and computer become more and more inseparable, both in life, learning or work, etc. Computers are widely used in daily life; however, health problems raise because people usually use and sit in front of the computer for a long time and some of them even sit in a bad posture. As a result, a wide range of height adjustable desks can be chosen in the current market, so that users can freely choose to stand or to sit in front of the computer by adjusting the height of the desk according to their own physical condition.
However, the structures of these conventional height adjustable desks are complex, resulting in high production costs, and so do the commodity prices. In addition, most of the height adjustment desks have only one desk top, which is mainly used to place the computer, keyboard and mouse. While the height of the desk top has been adjusted to meet the most appropriate reading height of the user's eyes, the user must raise his hands up to the height of the desk top in order to place them, and while this posture has been maintained for a period of time, excessive stress may apply on the user's shoulder that causes pain. On the other hand, if the height of the desk top has been adjusted to meet the most comfortable and natural height of the user's hands, the user has to stare down to see the screen. If the user stares down for a long period of time, consequently eye fatigues occur, and because the neck also bears with stress for a long time, stiff-neck or other severe harms might occur as well.